Plants need light, nutrients, water and air to survive. Although soil is the traditional medium that we use to grow plants, it is unnecessary; soil is merely a holding container for nutrients. Hydroponic systems do away with soil, using water to provide nutrients to the plants instead.
The nutrient solution in a hydroponics system is the key factor for plant growth. Fertilizer made specifically for hydroponics systems, containing all the nutrients a plant requires to survive, is mixed into water. Hydroponic solutions are diluted according to the instructions on the label. According to the Virginia Cooperative Extension, the final pH of a nutrient solution should be between 5 and 6 for optimum plant growth.
Water Culture Systems
Water culture systems are hydroponic constructs that grow plants without the need for a growing medium. The nutrient film technique provides nutrients to the plants through the application of a thin film of solution, which constantly runs along the plant roots. Plants are placed in a slanted trough that uses gravity to pull the nutrient solution into a reservoir at the bottom of the construct, which then pumps the solution back to the top to recycle it. Aeroponics grow plants in a container that holds the plants aloft with their roots exposed. A misting device sprays nutrient solution onto the plant roots. In the aeration method, plants are suspended above a nutrient solution, which is bubbled using an air pump so that it touches the plant roots.
Aggregate systems, according to the Virginia Cooperative Extension, use an inert material, or growing medium such as vermiculite, perlite, rockwool or clay pebbles, to surround plant roots. Media support the roots, allow air circulation and retain a small amount of nutrient solution for the plant to feed on. The flood-and-drain method is the most common aggregate system. Plants are held in pots filled with growing medium, then set into a large tray or pan. This tray is flooded with nutrient solution at regular intervals, wetting the growing media and providing nutrients to the plants.
Hydroponic systems are often used to grow plants indoors. No soil means plants are grown in smaller areas. Plants still need light to survive, so grow lamps are often necessary. According to the Alabama Cooperative Extension, most fruiting plants require between 8 and 10 hours of sunlight daily to produce properly, while foliage and ornamental plants need less. The temperature also requires close regulation. Most plants require between 70 and 80 degrees during the day and between 60 to 70 degrees during the evening for warm-weather plants, and 10 degrees lower for cool-season plants.
The nutrients solution is built with macro and micro nutrient. Macronutrients include the primary nutrients nitrogen (N); phosphorus (P); and potassium (K); and the secondary nutrients calcium (Ca); magnesium (Mg); and sulfur (S), according to the plants needs, says the Alabama Cooperative Extension. Micronutrients included in most hydroponic solutions are iron (Fe); manganese (Mn); boron (B); molybdenum (Mo); zinc (Zn); copper (Cu); and chlorine (Cl). These nutrients are required in small doses by most plants.